Semaglutide 15mg

At a glance

Strength

15 mg

Also known as

NN9535, NN-9535, NNC 0113-0217, semaglutida, semaglutidum

CAS number

910463-68-2

Molecular formula

C187H291N45O59

Molecular weight

4114 g/mol (FDA label: 4113.58 g/mol)

Sequence

H-Aib-EGTFTSDVSSYLEGQAA-K(gamma-Glu-2xAEEA-C18 diacid)-EFIAWLVRGRG-OH (31 residues, GLP-1(7-37) numbering: Aib8, Arg34, Lys26 acylated)

PubChem CID

56843331

What semaglutide is

Semaglutide is a GLP-1 receptor agonist that shares 94% of its sequence with human GLP-1 ³. Novo Nordisk scientists described its discovery in 2015 as the result of a search for a once-weekly successor to liraglutide, an earlier acylated GLP-1 analogue ¹. Their aim was higher albumin affinity together with full stability against metabolic degradation, and they found the fatty acid and the chemistry linking it to the peptide to be the key features ¹. In their assays, semaglutide bound the GLP-1 receptor with an affinity of 0.38 nM, three-fold weaker than liraglutide, while its albumin affinity was higher ¹. Semaglutide selectively binds to and activates the GLP-1 receptor ³. Tirzepatide acts at both the GIP and GLP-1 receptors ²¹, and Retatrutide at the GLP-1, GIP and glucagon receptors ²².

Chemical identity

PubChem lists semaglutide as CID 56843331, with the formula C187H291N45O59, a molecular weight of 4114 g/mol and CAS number 910463-68-2 ². FDA's prescribing information gives the same formula and a molecular weight of 4113.58 g/mol ³. Compared with human GLP-1, semaglutide carries 2-aminoisobutyric acid (Aib) at position 8 and arginine at position 34, and it is derivatised at lysine 26 ¹. The position 8 change protects the peptide from the enzyme dipeptidyl peptidase-4, and the position 34 change ensures that only one fatty diacid is attached ³. According to PubChem's systematic name, the lysine side chain carries a gamma-glutamic acid, two amino-ethoxy-ethoxy-acetic acid spacers and a 17-carboxyheptadecanoyl group, and the C-terminal glycine is a free acid ². FDA's label describes the substance as a white to almost white hygroscopic powder ³.

Why the salt form matters

FDA states that salt forms such as semaglutide sodium and semaglutide acetate are different active ingredients than are used in the approved drugs ⁹. The approved labels give the formula of the non-salt peptide, C187H291N45O59 ³. The agency adds that it has no information on whether these salts share the chemical and pharmacologic properties of the approved active ingredient ⁹. PubChem keeps a separate record for semaglutide acetate, CID 171360195, with the formula C189H295N45O61 and a molecular weight of 4174 g/mol ¹⁰. PubChem's acetate record (4174 g/mol) is heavier than the non-salt record (4114 g/mol) ²¹⁰.

Regulatory status

As of October 2026, FDA has approved semaglutide in several Novo Nordisk medicines ⁵⁶⁷⁸. Ozempic, a solution for subcutaneous use, was approved on December 5, 2017 as a new molecular entity ⁵. Its label lists use as an adjunct to diet and exercise for glycaemic control in adults with type 2 diabetes, cardiovascular risk reduction in adults with type 2 diabetes and established cardiovascular disease, and a kidney indication in adults with type 2 diabetes and chronic kidney disease ⁴. Rybelsus tablets were approved on September 20, 2019, and the same application now also lists tablets sold as Ozempic ⁶. Wegovy was approved on June 4, 2021, and its tablet form on December 22, 2025 ⁷⁸. The Wegovy label's indications include reducing the risk of major adverse cardiovascular events in adults with established cardiovascular disease and obesity or overweight and, under accelerated approval, noncirrhotic metabolic dysfunction-associated steatohepatitis (MASH) with moderate to advanced fibrosis ³. In the European Union, Ozempic received its marketing authorisation on 8 February 2018 and Wegovy on 6 January 2022 ¹¹¹². The semaglutide sold here is not any of these medicines: no approval covers its manufacture or quality, and it is sold only for laboratory research, never for use in people or animals.

Published research

The literature runs from structural biology to large outcome trials, and these are among the most cited studies.

• Discovery chemistry (2015). Structure-activity work on fatty acid and linker design; in mini-pigs the plasma half-life after intravenous administration was 46.1 hours ¹.
• Structural biology (2021). Cryo-electron microscopy structures of the GLP-1 receptor-Gs complex bound to semaglutide or taspoglutide, showing peptide contacts similar to GLP-1 but different motions within the receptor ¹³.
• Oral absorption (2018). Clinical and dog studies found that semaglutide co-formulated with the absorption enhancer SNAC is absorbed in the stomach, close to the tablet surface, by a transcellular route ¹⁴.
• SUSTAIN-6 (2016). A randomised, placebo-controlled trial in 3,297 people with type 2 diabetes over 104 weeks, with a composite primary outcome of cardiovascular death, nonfatal myocardial infarction or nonfatal stroke ¹⁵.
• STEP 1 (2021). A double-blind trial in 1,961 adults with obesity or overweight and no diabetes, with percentage change in body weight over 68 weeks as a coprimary end point ¹⁶.
• SELECT (2023). An event-driven trial in 17,604 people aged 45 or older with cardiovascular disease, a body-mass index of 27 or more and no diabetes, followed for a mean of 39.8 months ¹⁷.
• FLOW (2024). A trial in 3,533 people with type 2 diabetes and chronic kidney disease, stopped early after a prespecified interim analysis, measuring major kidney disease events ¹⁸.

This page describes the compound, not the clinical results of these trials.

What is not known

FDA's label states that semaglutide causes thyroid C-cell tumours in rodents at clinically relevant exposures, and that the human relevance of this finding has not been determined ³. FDA says it has no information on whether these salts have the same chemical and pharmacologic properties as the active ingredient in the approved drugs ⁹. A 2026 study by Novo Nordisk researchers found that compounded and follow-on semaglutide samples had impurity profiles different from the originator, including amino acid deletions and additions and unidentified impurities ²⁰. Its authors linked such differences to the source of the active ingredient, the manufacturing process and degradation during storage ²⁰. The approved medicines' peptide backbone is produced by yeast fermentation ³. A 2026 study noted that impurity profiles could be affected by the sourcing of the active pharmaceutical ingredient, the manufacturing process and degradation during storage ²⁰.

Laboratory storage and handling

FDA's label describes the substance as hygroscopic ³. In a 2026 thermal-stress study, solid semaglutide stayed amorphous and kept its native alpha-helical conformation up to 60 °C, its helical content fell almost to zero at 80 °C, and degradation and impurity formation increased with temperature ¹⁹. That study named temperature as a critical factor for solid-state stability ¹⁹.

Mass and analysis

PubChem gives the non-salt peptide an average molecular weight of 4114 g/mol and a monoisotopic mass of 4111.1 Da ². The 2026 thermal-stress study used reversed-phase HPLC and LC-HRMS to follow temperature-dependent degradation and impurity formation ¹⁹. Published certificates of analysis are listed with our lab results.